If someone has wrongfully taken from you, you are not to keep clamoring to get your possessions back. "The disciple loses less by letting his things be taken wrongfully than he would by with a selfish heart clamoring to have them returned." - Lenski.

But is Jesus saying that under no circumstances should we ever make any effort to regain stolen property? As we have seen, there are times when it is our duty to defend ourselves, our families and our property, John 18:22, 23; Acts 16:37-40. God has given us courts of law for that purpose. "What the present passage teaches is the very important truth that our personal attitude should never be one of taking revenge." - Hendriksen. See I Corinthians 6:7 and I Peter 2:21-24. We should never return evil for evil, even if our cause is just.